Interpretive Summary: Roller ginning, when compared to saw ginning, does the least amount of damage when separating the fiber from the seed. Roller ginning produces a superior fiber with excellent spinning potential. However, roller ginning is a slow and expensive process and, consequently, not used to gin the more abundant upland cotton crop. Improving the efficiency of the roller gin stand may allow upland cotton to be ginned at an economical rate. An experiment determined that ginning rate increased by modifying the stationary knife on a roller gin stand to allow a very small opening between the knife edge and ginning roller. (The stationary knife, one of the major components on a roller gin stand, has practically no opening as standard.) In addition, cottonseed linters' content was reduced and less scalping of the cottonseed was observed. The improvement in linters' content did not show a corresponding reduction in short fiber content of the lint. Foreign matter content in the lint was higher, although the additional foreign matter did not affect grade. All other fiber and cottonseed properties were not compromised. The improvements found in cottonseed linters content and ginning rate justify recommending the modified stationary knife. As roller ginning upland cotton becomes more cost-effective, the producer benefits by providing a superior fiber in greater demand and the consumer benefits by having a higher-quality product.

Technical Abstract:
An experiment determined the performance of experimental stationary knives when ginning upland cotton on a roller gin stand. Three knives were modified to allow an opening between the knife and the ginning roller of 0.095, 0.158, and 0.221 inches in depth, respectively. (A standard stationary knife has practically no opening.) The hypothesis is that linters (short fibers) cannot be pulled from the seed if the distance between the seed and the gripping point is increased beyond their length. As it is now, linters have a tendency to be scalped from the seed at the ginning point and allow shorter fibers (linters) to be included with the lint. If there is less scalping, there should be fewer short fibers. The only fiber and cottonseed properties that were affected by stationary-knife design included color reflectance, color yellowness, foreign matter content in the lint, and cottonseed linters' content. Foreign matter content in the lint increased as the opening between the stationary knives and ginning roller increased. The foreign matter content may have attributed to the fiber appearing different, and hence the differences in color reflectance and color yellowness. There were obvious differences, both visually and statistically, in cottonseed linters; the lowest linters' content occurred when using the stationary knife with the 0.095-inch-deep opening between the knife and ginning roller. Short fiber content was not affected by stationary-knife design as hypothesized. Ginning rate was affected by knife design; the highest rate was obtained with a 0.095-inch-deep opening between the stationary knife and ginning roller.